1. Field of the Invention
The present invention relates to a multilayer ceramic capacitor, and a method of manufacturing the multilayer ceramic capacitor.
2. Description of the Related Technology
The multilayer ceramic capacitor has a ceramic chip in a rectangular prism shape having a structure where a plurality of inner electrode layers are stacked via ceramic portions, and an edge of each of the inner electrode layers is alternately exposed on either end face in a length direction, and a pair of outer electrodes formed at both ends in the length direction of the ceramic chip. The ceramic portions include a dielectric such as BaTiO3, and the inner electrode layers and the outer electrodes includes a metal such as Ni.
The multilayer ceramic capacitor is manufactured through a step of stacking and pressing non-baked ceramic layers having non-baked inner electrode layers formed therein to obtain a non-baked ceramic chip, a step of forming non-baked outer electrodes at both ends in a length direction of the non-baked ceramic chip, and a step of baking the non-baked ceramic chip having the non-baked outer electrodes formed therein. When the metal configuring the inner electrode layers is a base metal, a step of reoxidation of the ceramic chip after baking is performed for controlling characteristics as necessary.
Certain background information may be found in Japanese Patent Documents JP-A-8-124785 and JP-A-2003-22930, each of which is incorporated by reference in it entirety.
The multilayer ceramic capacitor is generally mounted on various substrates by soldering, and when temperature of the capacitor itself is increased in soldering or voltage application after mounting, cracks may occur in the ceramic chip. The cracks occur mainly due to a fact that a thermal expansion coefficient of the inner electrode layers is higher than that of ceramic portions, that is, inner electrodes being thermally expanded cause stress mainly in side margin portions of the ceramic chip, and the stress causes occurrence of the cracks in the margin portions. Since the cracks in the ceramic chip may be a factor of significant change in capacitor characteristics, a measure is necessary, the measure being for preventing the cracks in the ceramic chip even when temperature of the capacitor itself is increased.
A capacitor in size 0603 (a reference value in a length direction is 0.6 mm and reference values in width and height directions are 0.3 mm) or size 0402 (a reference value in a length direction is 0.4 mm and reference values in width and height directions are 0.2 mm) is put into practical use with recent requirement of increase in capacity and size reduction, and the occurrence of cracks tends to be more significant with reduction in size of the multilayer ceramic capacitor, therefore the measure for preventing the cracks is now an extremely important technical development subject.
It is desirable to provide a multilayer ceramic capacitor in which occurrence of cracks in a ceramic chip can be prevented even when temperature of the capacitor itself is increased, and a method of manufacturing a multilayer ceramic capacitor by which the multilayer ceramic capacitor can be preferably manufactured.